Rotary vane pump

ABSTRACT

A rotary sliding vane machine in which the vane springs are positioned in chambers under the vane guide slots which are eccentrically arranged with respect to the guide slots. The springs may be either curved strip springs or cylindrical helical springs.

United States Patent inventor Hans Erdmann Neu-isenburg, Germany Appl.No. 3:136 I Filed Jan. 15, 1970 Patented Oct. 19, 1971 AssigneeIndustrial Electronic Hardware Corp.

New York, N.Y. Priority Jan. 17, 1969 Germany P 19 02 187.5

ROTARY VANE PUMP 5 Claims, 3 Drawing Figs.

11.8. C1 418/238, 418/266 Int. Cl F0lc 1/00 Field ofSearch 418/122, 123,266, 267, 238

[56] References Cited UNITED STATES PATENTS 339,827 4/1886 Tuck 418/266549,484 11/1895 Bach 418/266 616,766 12/1898 Bruce 418/266 X 886,1104/1908 Bromley 418/266 2,062,576 12/1936 Johnson 418/238 X 3,118,595l/1964 Fuhrmann 418/122 X FOREIGN PATENTS 939,643 4/1948 France 418/266ABSTRACT: A rotary sliding vane machine in which the vane springs arepositioned in chambers under the vane guide slots I which areeccentrically arranged with respect to the guide slots. The springs maybe either curved strip springs or cylindrical helical springs.

PATENTEDUCT 19 I97l SHEET 2 BF 2 ROTARY VANE PUMP BACKGROUND OF THEINVENTION Field of the Invention This invention relates to rotarysliding vane pumps and particularly to pumps of this type having springsfor pressing the vanes outward against the cam wall.

Description of Art In order to eliminate elastic deformations of therotor segments or guide of the segments under the influence of thehydraulic force exerted on the vanes of a rotary sliding vane pump, thetrend is to design the vanes and the guide slots in the rotor as thin aspossible to increase the strength of the segments. However, thisincreases the difficulty in designing springs for pressing the vanesagainst the cam plate curve and the use of coil springs acting againstthe bottom of the vanes is not practical with the thinner vanes.

To meet these requirements, a known vane-type machine has vanes whichare pressed against the cam plate by means of a bracketlike fasteningspring arranged on the side of the rotor. The ends of the bracket springare propped against two vanes located at an angle of 90 to each otherand the loop in the center of the spring is wound around a bolt fixed inthe rotor. The pump is designed so that when the vane at one end of thespring is being pushed into its slot by the cam surface the vane at theother end of the spring is sliding outward in its slot. Thus the bracketspring acts like a two-arrned lever which is resilient to compensate forthe tolerance.

A disadvantage of this arrangement is that the spring is arranged on theside of the rotor and the rotor can be pressed against the sidewallsonly in a narrow area in the peripheral region of the rotor therebycausing a sealing problem. Further, theguide slots of the vanescommunicate with one another through the cavity between the rotor andthe sidewall so that they can only be pressurized jointly. But in thepressure-controlled vane-type machines which are common today it isnecessary to vary the pressure continuously in the individual vaneslots. A vane-type machine of the kind in which a controlled pressureacting against the bottom of the vane stem assists the spring inpressing the vane against the cam plate could not be obtained with theabove-mentioned construction.

A further disadvantage of this bracket spring arrangement is that aneven number of vanes must be provided at suitable angular spacingbetween vanes. Also, the vanes may have a tendency to tilt in theirguide slots.

In pumps having vanes thick enough to have holes in the bottoms of thevanes for retaining coil springs, the thickness of the vanes reduces thestrength of the rotor segments between the vanes. The thick vanes alsohave a large absorption and displacement volume causing considerablequantities of pressure medium to flow through the control of the holesin the vane stem, thus unfavorably influencing the pressure ratiobetween the working chamber and the space under the vane stem andnecessitating a stiffer spring.

Moreover, in order to assure easy sliding in the vane slot, a certainlimiting value of the ratio of vane thickness to guiding length must notbe exceeded.

The copending application entitled Rotary Vane Pump by Fritz Ostwald,filed Jan. 15, 1970, Ser. No. 033,135 having the same assignee as thepresent application discloses one improved rotary vane machine in whichthe vanes are positioned in the working chamber and engage recesses inthe sides of the vane springs to press the vanes outward against the camsurface.

SUMMARY OF THE INVENTION An object of this invention is to provide animproved rotary vane machine having thin spring-loaded vanes and vaneslots which may be separately pressurized.

The present invention achieves this object by providing a chamber underthe vane stem arranged eccentrically with respect to the guide slot anda spring in the curved spring in the chamber having one end retained bya groove in the bottom of the vane stem and the other end retained by arecess in the rotor under the stem.

The spring may take several forms, such as curved strip spring havingholes punched in it to reduce the resistance to 5 movement within thepressure medium, a cylindrical helical spring having one arm acting onthe bottom of the vane stern and the other supported in a recess in therotor under the vane or a double cylindrical helical spring with the twoadjacent ends supported in a center hole in the space under the stem bya pin and the outer ends of the spring bent towards each other andconnected by a tube resting in a groove in the bottom surface of thevane stern. In axially long rotors it is possible to arrange severalsimilar springs in series in the space under the stem in the guide slot.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a partial sectional view ofa rotary vane machine embodying the present invention.

FIG. 2 is a partial sectional view of another embodiment of theinvention.

FIG. 3 is a plane view of a spring similar to the one shown in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. I shows a rotary slidingvane machine having a rotor 3 with vanes 32 slidable within guide slots2 in the rotor forming working chambers between successive vanes, theend walls not shown, and a cam plate 31. Cylindrical chambers I areformed at the bottom of the rotor guide slots and are positionedeccentrically with respect to the guide vanes. The thickness of thevanes is determined by the permissible bending stress, and the diameterof the eccentrically arranged chambers is determined by the size of theguide slots and the necessary strength of the rotor segments. The shapeof the chambers under the vane stems meet the design requirement formachines of smaller base circle diameter and with several working cyclesper revolution so that there is a smaller angle of rotation per stroke.The space under the stem and the corresponding hole in the controlflange should not exceed one third of the angle of rotation per strokeat the curve of the stroke.

Annular strip springs 12 forming an open ring are located in thechambers l with one end of the spring l2 supported in a groove I3 in thebottom surface of the vane stem and the other end held in a hole 14 inthe rotor directly underneath the vane. The spring has holes punched inits surface to reduce the resistance to displacement during high-speedoperation of the machine when the working fluid which may be oil isbeing displaced by the spring. In addition, to provide passages for theworking fluid, these holes tend to spread the bending stress equallyover the entire spring surface.

FIG. 2 shows another embodiment of the invention in which the spring 21is wound in a helical shape with one end of the spring resting in agroove 22 in the bottom of the vane stern and the other being supportedby a pin 23 in a countersunk hole 24 under the stern of the vane 32..

The spring shown in FIG. 3 is similar to that used in the embodimentshown in FIG. 2 except that it utilizes a pair of springs havingabutting ends 25 and 26 which are jointly supported by a pin under thevanes stern as shown in FIG. 2. The outer ends 27 and 28 are bent towardeach other and connected by a tube 29 which lies in the groove in thebottom surface of the vane stem. In this way the spring is securedagainst displacement and twisting. Joining the springs at both endsinsures that the spring does not fall apart if it breaks and this alsoreduces the pitching moments.

In axially long rotors it is possible to arrange several springs inseries under the stem thus increasing operational reliability in caseone of the springs breaks. In addition, this tends to prevent tilting ofthe rotor. Since the springs shown in these examples are restrained onlyat the ends and have no third point of support, there is a minimalamount of wear.

It will be appreciated that the invention illustrated and describedherein may be modified by those skilled in the art without deviatingfrom the spirit and scope of the invention as set forth in thefollowingclaims.

I claim as my invention:

1. A sliding vane rotary machine having vanes arranged in guide slots ofa rotor and pressed outwardly against a cam plate by springs whereineach of the springs are positioned in a chamber arranged under andeccentrically with respect to the guide slot, one end of each of thesprings being retained in a groove in the bottom surface in the vanestem while the other end is supported at a point in the rotor directlyin line with the vane stem. in the rotor directly in the vane stem.

2. The sliding vane rotary machine of claim 1 wherein the spring is astrip spring having a C-shape.

3. The sliding vane rotary machine of claim 2 wherein the strip springhas holes in its surface.

4. The sliding vane rotary machine of claim 1 wherein the spring is acylindrical helical spring having one end supported in a groove in thebottom surface of the vane stem and the other end supported at a pointdirectly under the vane stem.

5. The sliding vane rotary machine of claim 4 wherein the spring is twocylindrical helical springs having abutting ends which are connected andjointly supported by a pin resting in a central hole under the vane stemand the outer ends of the spring are bent toward each other andconnected by a tube which rests in the groove in the bottom of the vanestem.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. ,276Dated camber 19, 1971 Inventor Hana Erdmann It is certified that errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

In the headin after "Assignee", change "Industrial Electronic HardwareCorp." to read --Internationa1 Telephone and Telegraph Corporat1on--.

Signed and sealed this 30th day of May 1972.

SEAL) A the s b:

EDWARD PLFLETCHEFQJR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents M PO-105O (10-69) USCOMM-DC BOSTG-FOQ US GOVERNMENT PIINYINGOFFICE IDlI l)35$-3ll

1. A sliding vane rotary machine having vanes arranged in guide slots ofa rotor and pressed outwardly against a cam plate by springs whereineach of the springs are positioned in a chamber arranged under andeccentrically with respect to the guide slot, one end of each of thesprings being retained in a groove in the bottom surface in the vanestem while the other end is supported at a point in the rotor directlyin line with the vane stem. in the rotor directly in the vane stem. 2.The sliding vane rotary machine of claim 1 wherein the spring is a stripspring having a C-shape.
 3. The sliding vane rotary machine of claim 2wherein the strip spring has holes in its surface.
 4. The sliding vanerotary machine of claim 1 wherein the spring is a cylindrical helicalspring having one end supported in a groove in the bottom surface of thevane stem and the other end supported at a point directly under the vanestem.
 5. The sliding vane rotary machine of claim 4 wherein the springis two cylindrical helical springs having abutting ends which areconnected and jointly supported by a pin resting in a central hole underthe vane stem and the outer ends of the spring are bent toward eachother and connected by a tube which rests in the groove in the bottom ofthe vane stem.